Electronic devices such as mobile phones and smartphones include a card connector enabling the use of various types of cards such as SIM (Subscriber Identity Module) cards. A sealed card connector has been proposed which can be used under conditions in which the electronic device is exposed to rain and dust (see, for example, Patent Document 1).
FIG. 18 is a diagram showing a card connector of the prior art.
In this drawing, 811 is a housing for a card connector made of an insulating material. The housing 811 has side wall portions 898 arranged inside and the side wall portions 898 are secured to the case of the electronic device. The housing 811 includes a plurality of terminals 851. When a card holder 961 housing a card is inserted into the card connector, the terminals 851 make contact with the corresponding connecting pads on the card.
An opening 898a is formed in a side wall portion 898 at a location corresponding to an insertion slot for the card connector. The card holder 961 is inserted into the card connector via this opening 898a. 
When the card holder 961 has been inserted into the card connector, as shown in the drawing, the rear end surface 961b of the rear frame portion 961a of the card holder 961 is flush with the outer surfaces 898b of the side wall portions 898. A gasket 971 is attached to the outer periphery of the rear frame portion 961a of the card holder 961, and the gasket 971 seals the gap between the inner peripheral surface of the opening 898a and the outer peripheral surface of the rear frame portion 961a to protect the card connector from infiltration by water, dust, and debris.
Patent Document 1: JP 08-335255 A